Hosta, did the ad give the name and location of the gallery? Have you checked it out on google maps? When I order from a company, I use google earth to look at their store. Do I trust very much these days? No!
edited to add: The people I trust the most seem to be on this quilt site and another art site where I'm also a member. Ebay has protections built in; Craigs List is like walking down the ally in the middle of the night! Good Luck.